Steam reformers, modules, and methods of use

ABSTRACT

The present disclosure is directed to steam reformers for the production of a hydrogen rich reformate, comprising a shell having a first end, a second end, and a passage extending generally between the first end and the second end of the shell, and at least one heat source disposed about the second end of the shell. The shell comprises at least one conduit member comprising at least one thermally emissive and high radiant emissivity material, at least partially disposed within the shell cavity. The shell further comprises at least one reactor module at least a portion of which is disposed within the shell cavity and about the at least one conduit member and comprises at least one reforming catalyst. The disclosure is also directed to methods of producing a hydrogen reformate utilizing the steam reformers, comprising the steps of combusting a combustible mixture in a burner to produce a combustion exhaust that interacts with the steam reactor module(s) through surface to surface radiation and convection heat transfer, and reforming a hydrocarbon fuel mixed with steam in the steam reformers to produce a hydrogen-containing reformate. The present disclosure is further directed to reactor modules for use with the above steam reformers and methods of producing a hydrogen reformate.

This application is a divisional of U.S. patent application Ser. No.13/917,367, filed Jun. 13, 2013, which claims the benefit of U.S.Provisional Application No. 61/659,898, filed Jun. 14, 2012, which areboth incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a steam reformer for the production ofa hydrogen reformate, a reactor module for use in the steam reformers,and methods of producing a hydrogen reformate using the reformer ormodule.

BACKGROUND

Steam reforming is a method for producing hydrogen from hydrocarbons,such as methane. The basic chemistry of steam reforming uses atemperature-driven reaction of a hydrocarbon with water to produce a“synthesis gas,” a mixture of primarily hydrogen, water, carbonmonoxide, and carbon dioxide as well as nitrogen for ammonia synthesis.This synthesis gas is sometimes more generally referred to as a“reformate” in which nitrogen can be just a trace amount of one element.

A “steam reformer” or “burner/reformer assembly” can comprise two flowregions. The first region can provide thermal energy from hot gases,produced, for example, by the combustion of fuel and oxygen, and calledthe “burner zone.” The second region allows an endothermic steamreforming reaction between fuel and steam, and is called the “reformingzone,” “reformer module,” or “reforming tubes.” These two flow regionsare usually physically separated by a heat exchange boundary.

One challenge in steam reforming is transferring enough energy throughthe heat exchange boundary to sustain the reaction at a desired reactiontemperature. The reaction temperature affects hydrocarbon conversionequilibrium and reaction kinetics. Higher reaction temperature in thereforming zone corresponds to a lower heat transfer resistance, higherhydrocarbon conversion, and a lower amount of residual hydrocarbonremaining in the reformate. This reaction can be accelerated by using acatalyst containing a material such as, for example, nickel, a preciousmetal, or another material containing a special promoter.

High reaction temperatures, however, can cause severe thermal stress,corrosion, creep, and fatigue in metal components of the heat exchangeboundary and/or catalyst. Conversely, low reaction temperatures in thereforming zone can reduce metal stress, corrosion, creep and fatigue,and lead to lower hydrocarbon conversions. Higher amounts ofhydrocarbons in the reformate can cause difficulties in a subsequenthydrogen separation stage. Furthermore, the more hydrocarbons left inthe reformate, the less efficient the steam reformer system becomes.This leads to a higher cost of hydrogen and a higher level of carbondioxide (a greenhouse gas) emissions per unit of hydrogen produced.

Large scale industrial steam reformers often use multiple reformer tubesas the heat exchange boundary, surrounded by “hot-gas impingement” styleburner modules. A burner fuel-air mixture can be fired in the spacearound the tubes, either directly toward the reformer tubes, along them,or parallel to the reformer tubes from the top and/or from the bottom.

The reforming zones of such steam reformers often operate at hightemperature (>850° C.) and pressure (as high as ˜30 bar), runningcontinuously with few startup-shutdown cycles to prolong the usable lifeof the tubes. To control the temperature profile along the length of thereactor tubes, large industrial reformers sometimes use multiple burnerheads along the reformer tubes to avoid the high local temperatures thatare typically required if a single burner is used.

Due to the large cost of construction of centralized reforming plants,many economic studies of a hydrogen economy have noted the potentialadvantages of smaller scale distributed hydrogen production for use in,for example, appliances or other devices. For many applications, thedemand of hydrogen is likely to be intermittent (non-limiting examplesinclude a hydrogen fueling station serving a fleet of fuel cell orCNG/H2 capable vehicles to a residential-scale hydrogen refuelingappliance, a merchant hydrogen appliance, a reformate productionappliance, a combined heat and power (CHP) appliance, and a combinedheat, hydrogen, and power (CHHP) appliance). To run efficiently, thesehydrogen producing devices must start and stop many times whilemaintaining their performance and structural integrity. Small scalereformers can generally not afford the expense, space demand, andcomplexity of staged combustion, and often use a single stage in situcombustion to supply heat to the reforming reaction. Single stagecombustion, however, often results in localized high temperatures on thereformer tubes. Frequent startup-shutdown cycles and temperatureexcursions repeatedly expose reformer components to severe thermalgradients and temperature spikes, both of which cause high thermalstresses, potentially inducing failures in a relatively short period oftime. Additionally, heat transfer effectiveness is diminished along thecombustion products flow direction on account of their fallingtemperature (i.e. heat transfer theory provides that the radiativecomponent of heat flux scales with temperature to the 4^(th) power).

SUMMARY

In contrast to prior art steam reformers, the present disclosureprovides a cost-effective (reduced capital, increased efficiency, andenhanced life) steam reformer architecture in which at least one burnerzone is designed and configured to promote radiative and convective heattransfer, both in general along the heat exchange boundary, as well aspreferentially in the direction of flow. The steam reformers disclosedherein aim to overcome these and other limitations of prior systems. Itis accordingly an object of the present disclosure to provide a steamreformer for the production of a hydrogen reform ate. The steam reformercan comprise a shell having a cavity, and at least one heat sourceconfigured to heat a fluid supplied to the cavity. The shell cancomprise at least one conduit member comprising a thermally emissivematerial and having a passage extending generally there through. In someembodiments, the passage guides the heated fluid from the heat source tothe cavity. In other embodiments, the conduit member is a radiant and/oremissivity conduit member at least partially disposed within the cavity.In still other embodiments, a first end of the at least one conduitmember can be in fluid communication with the cavity, and a second endof the conduit can be in fluid communication with the at least one heatsource. In other embodiments, the conduit member comprises a thermallyemissive material to provide a radiation emitting surface within thecavity.

The shell can also comprise at least one reactor module at leastpartially disposed within the cavity to receive heat supplied by theheated fluid, and located about the at least one conduit member toreceive radiative heat supplied by the conduit member. In someembodiments, at least one of the at least one reactor modules cancomprise at least one reforming catalyst. In some embodiments, the shelloptionally can comprise at least one insulating member disposed aboutthe cavity. In some embodiments, heat can be absorbed and radiated intothe cavity by the at least one radiant conduit member when the heatedfluid traverses the passage of the at least one radiant conduit memberto the cavity.

The shell may further comprise at least one deflector disposed about thefirst end of the at least one conduit member. In some embodiments, theat least one deflector can be interposed between the first end of the atleast one conduit member and the at least one reactor module.

It is accordingly another object of the present disclosure to provide asteam reformer for the production of hydrogen reformate, comprising ashell, which can be cylindrical, comprising a cavity, a bottom portion,a top portion, and an insulating member. The bottom portion can comprisean opening comprising, in one embodiment, a heat source configured toheat a fluid supplied to the cavity, and a silicon carbide hollowconduit comprising openings at both ends. A first end of the siliconcarbide hollow conduit can be disposed within the cavity and opens intothe cavity, and a second end of the silicon carbide hollow conduit canbe attached to the shell bottom and opens to the shell exterior. In someembodiments, the at least one heat source can be in fluid communicationwith the conduit second end and the silicon carbide hollow conduit canguide the heated fluid from the heat source to the cavity. As usedherein, hollow is understood to mean empty inside such that a siliconcarbide hollow conduit can comprise a passage from the heat source tothe shell cavity by the fluid connection of the first end, hollowinside, and second end of the silicon carbide hollow conduit. In otherembodiments, a silicon carbide hollow conduit can include a surfacecoating on the hollow inside surface of the silicon carbide hollowconduit, or an extended surface.

The top portion of the cylindrical shell can comprise at least oneopening configured to receive a cylindrical reactor module that extendsinto the cavity to receive heat supplied by the heated fluid. In someembodiments, the cylindrical reactor module can comprise at least onereforming catalyst.

In some embodiments, a portion of the at least one reactor moduledisposed within the cavity can freely hang within the cavity withoutattachment to the cavity. In other embodiments, a portion of the reactormodule disposed within the cavity can be positioned about the siliconcarbide hollow conduit to receive radiative heat supplied by theconduit. In still other embodiments, the space between the at least onecylindrical reactor module and the silicon carbide hollow conduit can befree of insulation, packing, or other materials designed to thermallyisolate the at least one reactor module from the conduit. In someembodiments, the portion of the at least one reactor module that residesoutside of the cylindrical shell can be individually and removablyattached to the top portion of the cylindrical shell. In otherembodiments, the portion of the at least one reactor module that residesoutside of the cylindrical shell can be individually and removablyattached to the bottom portion of the cylindrical shell. In someembodiments, this can allow for individual insertion, removal, and/orreplacement of one or more reactor modules.

In some embodiments, the steam reformer can comprise an insulatingmember disposed about the cavity between the shell inner surface and thereactor module. In one embodiment, a surface of the insulating memberfacing the reactor module can be shaped to reflect radiant heat from theradiant conduit member and reactor module, and heated fluid back to thereactor module.

The shell may further comprise at least one reflector disposed about theat least one insulating member. In some embodiments, the at least onereflector can be interposed between the at least one insulating memberand the at least one reaction module.

It is accordingly yet another object of the present disclosure toprovide a method of producing hydrogen comprising heating a fluid withthe heat source of the steam reformers disclosed above, communicatingthe heated fluid through the at least one radiant conduit member to thecavity to heat the reactor module, and reforming at least a portion of areactant in the reactor module to a hydrogen reformate. In someembodiments, the method can comprise heating the conduit member of thesteam reformers disclosed above with the heat source and radiating heatfrom the at least one conduit member to the reactor module.

In another embodiment, the method comprises heating the fluid with theheat source, heating the at least one radiant conduit member with theheated fluid, radiating heat from the at least one conduit member to thereactor module, and reforming at least a portion of a reactant stream inthe reactor module to a hydrogen reformate.

It is a further object of the present disclosure to provide a reactormodule. In some embodiments, the reactor module can comprise a thermallyconductive shell having a cavity, and a tube assembly disposed at leastpartially within the cavity. In some embodiments, the tube assembly cancomprise at least one catalyst bed disposed within the cavity to receiveheat conducted by the thermally conductive shell, the at least onecatalyst bed comprising at least one reforming catalyst. In otherembodiments, the reforming catalyst can comprise at least one of a steamreforming catalyst, a pre-steam reforming catalyst, an oxidationcatalyst, a partial oxidation catalyst, and a water-gas-shift catalyst.The reforming catalyst can be in any form or structure and of anyappropriate size including, for example, foams, monoliths, spheres,tablets, cylinders, stars, tri-lobes, quadra-lobes, pellets, granules,honeycombs, cubes, plates, felts, particles, powders, structured forms,reticulated foam, foam pellets/chips/disc, on metal, metal alloy, and/orceramic support, and combinations thereof. In some embodiments, thereformer catalyst can be place in or coated on a catalytic heatconverter, metal or metal alloy support, or on carbon nanotubes in or onany of the foregoing.

In still other embodiments, the tube assembly also can comprise at leastone first channel configured to provide at least one reactant stream toat least a portion of the at least one catalyst bed, and at least onesecond channel configured to provide at least one product stream from atleast a portion of the at least one catalyst bed. In some embodiments,the tube assembly also can comprise at least one partition wallinterposed between at least a portion of the at least one first channeland at least a portion of the at least one second channel. In someembodiments, heat can be exchanged through the at least one partitioningwall between at least a portion of the product stream and at least aportion of the reactant stream. In some embodiments, said heat exchangesubstantially occurs within the cavity. In other embodiments, at least aportion of the reactant stream converts to the at least one productstream when at least a portion of the reactant stream interacts with atleast a portion of the at least one reforming catalyst.

In other embodiments, the reactor module can comprise a first fluidconduit having a first end including a product exit port, a second end,and a passage extending generally between the first end and the secondend of the first fluid conduit wherein at least part of the passage ofthe first fluid conduit includes at least one reforming catalyst, asecond fluid conduit having a first end, a second end, and a passageextending generally between the first end and the second end of thesecond fluid conduit, a third fluid conduit having a first end, a secondend, and a passage extending generally between the first end and thesecond end of the third fluid conduit, and a fourth fluid conduit havinga first end including a reactant entry port, a second end, and a passageextending generally between the first end and the second of the fourthfluid conduit. In some embodiments, the second ends of the first andfourth fluid conduits can be fluidly connected, the second ends of thethird and second fluid conduits can be fluidly connected, and the firstends of the fourth and third fluid conduits can be fluidly connected. Insome embodiments, at least part of the passage of the fourth fluidconduit includes at least one reforming catalyst.

In other embodiments, the first fluid conduit can be at least partiallylocated within the passage of the second fluid conduit, the second fluidconduit can be at least partially located within the passage of thethird fluid conduit, and the third fluid conduit can be at leastpartially located within the passage of the fourth fluid conduit.

In still other embodiments, the first end of the first fluid conduit caninclude a reactant entry port. In other embodiments, the first end ofthe second fluid conduit includes a product exit port.

Additional objects and advantages of the present disclosure will be setforth in part in the description which follows, and in part will beobvious from the description, or can be learned by practice of thedisclosure. The objects and advantages of the present disclosure will berealized and attained by means of the elements and combinationsparticularly pointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 depicts a cross-sectional interior view of one embodiment of asteam reformer of the present disclosure.

FIG. 2 depicts a cross-sectional interior view of an embodiment of asteam reformer of the present disclosure.

FIG. 3 depicts a first end of a shell of a steam reformer of the presentdisclosure.

FIG. 4 depicts one embodiment of an insulating member of the presentdisclosure.

FIG. 5 depicts a cross-sectional interior view of an embodiment of asteam reformer of the present disclosure.

FIG. 6 depicts a cross-sectional internal view of a reactor module ofthe present disclosure.

FIG. 7 depicts one embodiment of a steam reformer of the presentdisclosure further comprising at least one deflector.

FIG. 8 depicts a cross-sectional interior view of an embodiment of asteam reformer of the present disclosure further comprising at least onedeflector and at least one reflector.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 depicts one embodiment of the present disclosure. Steam reformer1 can comprise a shell 10, wherein part or all of shell 10 can beconstructed of metal, ceramic, high-temperature polymers, or the like.Various manufacturing methods can be used to produce shell 10. Forexample, manufacturing can include metal pipe, rolling metal sheets,welding metal plates, or other methods known in the art. Shell 10 can beformed into a cylindrical, circular, rectangular, oblong, elliptical,square, rectangular, or other geometric shapes, and whosecross-sectional form may vary along their length.

Steam reformer 1 can include a heat source 30 configured to heat a fluidsupplied to a cavity 20 contained within shell 10. Heat source 30 canproduce a hot gas by any means known in the art, such as, burning afuel, converting electricity into heat, using solar energy, orcombinations thereof. In one embodiment, heat source 30 is a hightemperature heat source. In some embodiments, heat source 30 can belocated near a second end of shell 10 as shown in FIG. 1. In otherembodiments, heat source 30 can be located at either end of shell 10, orremote from steam reformer 1.

Steam reformer 1 can also comprise conduit member 40 comprising a firstend 42, a second end 44, and a passage 46 extending generally betweenfirst end 42 and second end 44. Conduit member 40 can include acylindrical tube, pipe, or any other structure. Conduit member 40 can bein a circular, rectangular, oblong, elliptical, or other geometricshapes and whose cross-sectional form may vary along their length. Insome embodiments, the size and shape of conduit member 40 can vary alongits length to change the geometry (e.g. cross-sectional flow area) ofthe flow passage, as well as the heat exchange boundary exposed toradiative heat transfer. In some embodiments, second end 44 can accept afluid as an input, and 44 first end 42 can discharge a fluid as anoutputs into cavity 20.

In one embodiment, Conduit 40 is configured to radiate heat into cavity20. For example, in some embodiments (1) the materials of constructioncan be chosen (e.g. on the basis of thermal conductivity and/oremissivity) to influence thermal gradients in conduit member 40 (whichaffects the surface temperature distribution and associated radiativeemission); and/or (2) the shape and surface characteristics (e.g.roughness, texture, contour, or emissivity-enhancing or reducingcoatings) of conduit member 40 can be altered to enhance or reduce theintensity and/or directionality of local radiative heat flux. Conduit 40can be constructed of metal, metal alloy, and inorganic material such asglass, porcelain, ceramic, silicon carbide, and combinations thereof,and made by methods known in the art. Conduit member 40 can includematerials which are robust under thermal cycling, high temperatures, andthermal shock, and which have favorable heat transfer characteristics.In some embodiments, conduit member 40 can comprise at least onethermally emissive material selected from metal, metal alloy, porcelain,glass, ceramic, silicon carbide, combinations thereof. Non-limitingexamples of metal include tungsten, nickel, chromium, iron, aluminum,and stainless steel. Non-limiting examples of metal alloys includealloys comprising at least one of nickel, iron, cobalt, chromium,molybdenum, tungsten, silicon, manganese, aluminum, carbon, and mixturesor combinations thereof.

In one embodiment, a metal alloy comprises 57% nickel, up to 3% iron, upto 5% cobalt, 22% chromium, 2% molybdenum, 14% tungsten, 0.4% silicon,0.5% manganese, 0.3% aluminum, 0.10% carbon, 0.015% boron, and 0.01%lanthanum and is sold as, for example, Haynes 230®. In anotherembodiment, a metal alloy comprises 75% nickel, 3% iron, up to 2%chromium, 16% cobalt, up to 0.2% silicon, up to 0.5% manganese, 4.5%aluminum, 0.04% carbon, 0.01% yttrium, and up to 0.1% zirconium and issold as, for example, Haynes 214®. In still other embodiments, a metalalloy comprises 20% nickel, 31% iron, 18% chromium, 22% cobalt, 3%molybdenum, 2.5% tungsten, 0.4% silicon, 1% manganese, 0.2% aluminum,0.10% carbon, 0.2% nitrogen, 0.6% tantalum, 0.02% lanthanum, and 0.01%zirconium, and is sold as, for example, Haynes 556®. In still furtherembodiments, a metal alloy comprises 11% nickel, 65% iron, 21% chromium,up to 0.8% manganese, 1.7% silicone, 0.17% nitrogen, 0.07% carbon and issold as, for example, 253MA®. In some embodiments, a metal alloycomprises 33% iron, 37% nickel, up to 3% cobalt, 25% chromium, up to2.5% molybdenum, up to 2.5% niobium, 0.7% manganese, 0.7% silicon, 0.6%silicon, 0.20% nitrogen % aluminum, 0.05% carbon, and 0.004% boron, andis sold as, for example, Haynes HR-120® alloy. In other embodiments, ametal alloy comprises 37% nickel, 29% cobalt, 28% chromium, up to 2%iron, 2.75% silicon, 0.5% manganese, 0.5% titanium, 0.05% carbon, up to1% tungsten, up to 1% molybdenum, and up to 1% niobium, and is sold as,for example, Haynes HR-160® alloy. In other embodiments, the at leastone thermally emissive material can be silicon carbide.

In one embodiment, conduit member 40 comprises a solid tube. Solid asused herein means non-permeable to gas flow wherein the heated fluidentering conduit member 40 comprising a solid tube can only enter cavity20 by traversing passage 46 and second end 44.

In some embodiments, second end 44 of conduit member 40 can be in fluidcommunication with heat source 30. In still other embodiments, first end42 of conduit member 40 can also be in fluid communication with cavity20. Conduit member 40 can be peripherally sealed at second end 44 whereit accepts inputs from heat source 30, to prevent fluid bypass, i.e. toprevent fluid from flowing from the interior of conduit 40 to theexterior of conduit 40 via a path not passing through first end 42.

Convection is the concerted, collective movement of ensembles ofmolecules within fluids (i.e. liquids, gases) and rheids. Convectiveheat transfer is the transfer of heat by the fluid molecular movement onthe surface of the transfer boundary. Convective heat transfer does notoccur through a solid material. The heat transfer occurred through asolid, liquid, or stagnant gas is called conductive heat transfer.Thermal radiation, another type of heat transfer, is electromagneticradiation generated by the thermal motion of charged particles inmatter. Thus, a hot solid material can heat another solid materialwithout making physical contact by radiant heat transfer.

In some embodiments, heat can be communicated convectively from heatsource 30 to cavity 20 by the flow of the heated fluid from heat source30 through conduit member 40 into cavity 20. Conduit member 40 cancontain and direct the flow of fluid, for example, a combination offuel, oxidant, inerts, and combustion products from heat source 30 whichheats conduit member 40. Heat can then be transferred convectively andradiantly to the region bounding conduit member 40. Conduit member 40which can have a very high surface temperature, can thus act as aradiant heat source. As such, heat can be emitted radiantly to thesurrounding surfaces by a substantial portion of conduit member 40.Thus, in certain embodiments, a surface of the solid radiant conduitmember is in hot fluid communication with heat-accepting surfaces withinthe cavity while emitting radiant energy to the surrounding surfaces ofa reactor module and an insulation member. In some embodiments, a lengthof the radiant conduit member can be close to the length of the reactormodules within the cavity. The length of the radiant conduit member canaffect the radiant heat transfer.

Steam reformer 1 can also comprise at least one reactor module 50 forthe catalytic conversion of a reactant stream to a hydrogen reformatestream. In some embodiments, a portion of the reactor module disposedwithin the cavity can be located about the radiant conduit member toreceive radiant heat supplied by the radiant surface of the solidradiant conduit member. Reactor module 50 can include a cylindricaltube, pipe, or any other structure. Reactor module 50 can be in acircular, rectangular, oblong, elliptical, or other geometric shapes andwhose cross-sectional form may vary along their length. In someembodiments, the size and shape of reactor module 50 can vary along itslength to change the geometry (e.g. cross-sectional flow area) of theflow passage, as well as the heat exchange boundary exposed to radiativeheat transfer.

Reactor module 50 can be constructed of at least one thermallyconductive material. For example, in some embodiments, reactor module 50can comprise at least one thermally conductive and radiant emissivityand/or absorptivity material selected from metal, metal alloy,porcelain, glass, ceramic, silicon carbide, and combinations thereof. Insome embodiments, reformer 50 can comprise a high temperature alloy, andcan be constructed by cutting, welding, casting, or any other methodknown in the art. Non-limiting examples of metal include tungsten,nickel, chromium, iron, aluminum, stainless steel, and mixtures orcombinations thereof. Non-limiting examples of metal alloys includealloys comprising at least one of nickel, iron, cobalt, chromium,molybdenum, tungsten, silicon, manganese, aluminum, carbon, and mixturesor combinations thereof.

In one embodiment of the present disclosure, a metal alloy comprises 57%nickel, up to 3% iron, up to 5% cobalt, 22% chromium, 2% molybdenum, 14%tungsten, 0.4% silicon, 0.5% manganese, 0.3% aluminum, 0.10% carbon,0.015% boron, and 0.01% lanthanum and is sold as, for example, Haynes230®. In another embodiment, a metal alloy comprises 75% nickel, 3%iron, up to 2% chromium, 16% cobalt, up to 0.2% silicon, up to 0.5%manganese, 4.5% aluminum, 0.04% carbon, 0.01% yttrium, and up to 0.1%zirconium and is sold as, for example, Haynes 214®. In still otherembodiments, a metal alloy comprises 20% nickel, 31% iron, 18% chromium,22% cobalt, 3% molybdenum, 2.5% tungsten, 0.4% silicon, 1% manganese,0.2% aluminum, 0.10% carbon, 0.2% nitrogen, 0.6% tantalum, 0.02%lanthanum, and 0.01% zirconium, and is sold as, for example, Haynes556®. In still further embodiments, a metal alloy comprises 11% nickel,65% iron, 21% chromium, up to 0.8% manganese, 1.7% silicone, 0.17%nitrogen, 0.07% carbon and is sold as, for example, 253MA®. In someembodiments, a metal alloy comprises 33% iron, 37% nickel, up to 3%cobalt, 25% chromium, up to 2.5% molybdenum, up to 2.5% niobium, 0.7%manganese, 0.7% silicon, 0.6% silicon, 0.20% nitrogen % aluminum, 0.05%carbon, and 0.004% boron, and is sold as, for example, Haynes HR-120®alloy. In other embodiments, a metal alloy comprises 37% nickel, 29%cobalt, 28% chromium, up to 2% iron, 2.75% silicon, 0.5% manganese, 0.5%titanium, 0.05% carbon, up to 1% tungsten, up to 1% molybdenum, and upto 1% niobium, and is sold as, for example, Haynes HR-160® alloy. Thereactor module can comprise a high absorptivity surface to acceptradiant energy from the surface of the radiant conduit member.

In some embodiments, the length of conduit member 40 can be equal to orless than the length of reactor module 50 which can affect radiant heattransfer. In other embodiments, the length of conduit member 40 can begreater than the length of reactor module 50. In this embodiment, thecontrol factor of radiant heat transfer can be the shortage of thesurface area of the conduit member 40. In still other embodiments,reactor module 50 can comprise at least one reforming catalyst such as asteam methane reforming catalyst, a pre-steam reforming, an oxidation,partial oxidation or a water-gas-shift catalyst. The reforming catalystcan fill the catalyst bed, wholly or partially, in any form discussedabove such as granular, pelletized catalyst media, and coated on asupport material such as a foam inserted into the catalyst bed. In someembodiments, the reforming catalyst bed absorbs radiant energy from thesurface of the radiant conduit member via the high absorptivity surfaceof reactor module 50.

In some embodiments, reactor module 50 can be at least partiallydisposed within cavity 20 to receive heat supplied by the heated fluid,and located about conduit member 40 to receive radiative heat suppliedby conduit member 40. Combustion products from heat source 30 exitingfirst end 42 of conduit member 40 can come into direct contact with theexterior surfaces of reforming module 50. In some embodiments, heat canbe communicated convectively from heat source 30 to cavity 20 andreactor module 50 by the flow of the heated fluid from heat source 30through conduit member 40 into cavity 20.

At steady state operation of a steam reformer of the present disclosure,reactor module 50 can receive heat comprising convective heat from theheated fluid and radiant heat radiated by conduit member 40. In someembodiments, radiant heat comprises about 10% to about 90% of the totalheat received by reactor module 50 at steady state operation of a steamreformer of the present disclosure. As used herein, steady state isunderstood to mean operating conditions which are generally constantwith time. For example, radiant heat can comprise about 20% to about80%, about 30% to about 70%, about 40% to about 60%, about 50% to about90%, about 60% to about 90%, about 70% to about 90%, about 80% to about90%, about 60% to about 80%, about 60% to about 70%, or about 70% toabout 80% of the total heat received by the reactor module at steadystate operation of a steam reformer of the present disclosure. In otherembodiments, radiant heat comprises about 10%, about 20%, about 30%,about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% ofthe total heat received by the reactor module at steady state operationof a steam reformer of the present disclosure.

In some embodiments, the amount of radiant heat of the total heatreceived by the reactor module exceeds the amount of convective heat ofthe total heat received by reactor module 50 at steady state operationof a steam reformer of the present disclosure. For example, the amountof radiant heat received by the reactor module can be about 10% to about200% greater, about 20% to about 180% greater, about 30% to about 170%greater, about 40% to about 160% greater, about 50% to about 150%greater, about 60% to about 140% greater, about 70% to about 130%greater, about 80% to about 120% greater, about 90% to about 110%greater than the amount of convective heat received by the reactormodule at steady state operation of a steam reformer of the presentdisclosure. In some embodiments, radiant heat is about 100%, about 200%,about 300%, about 400%, or about 450% greater than the amount ofconvective heat received by reactor module 50 at steady state operationof a steam reformer of the present disclosure.

In some embodiments, steam reformer 1 can optionally comprise insulatingmembers inside or on its inner surface to protect shell 10 and to reduceheat loss. For example, in some embodiments, insulating member 60 can bedisposed about an inner surface of shell 10 and reactor module 50. Inother embodiments, shell 10 also can comprise insulating member 65disposed about the inner surface of shell 10 about an upper portion ofcavity 20. Insulating members 60 and 65 can comprise a refractoryceramic material. For example, in some embodiments (1) the materials ofconstruction can be chosen (e.g. on the basis of thermal conductivityand/or emisivity) to influence thermal gradients in insulating members60 and 65 (which affects the surface temperature distribution andassociated radiative emission); and/or (2) the shape and surfacecharacteristics (e.g. roughness, texture, contour, oremissivity-enhancing or reducing coatings) of insulating members 60 and65 can be altered to enhance or reduce the intensity and/ordirectionality of local radiative heat flux.

Insulating members 65 and 60 can be made by such methods as machining,casting, or other methods known in the art. Insulating members 60 and 65can be in a circular, rectangular, oblong, elliptical, or othergeometric shapes and whose cross-sectional form may vary along theirlength. In some embodiments, the size and shape of insulating members 60and 65 can vary along its length to change the geometry (e.g.cross-sectional flow area) of the flow passage, as well as the heatexchange boundary exposed to radiative heat transfer.

FIG. 2 depicts an embodiment of the present disclosure wherein theradiant conduit 40 can be a single cylindrical tube made of siliconcarbide, positioned in the center of an array of reforming modules 50.Hot fluid can flow through passage 46 of conduit 40 from the bottom ofthe conduit to the top of the conduit as represented by the arrowtraversing passage 46, heating a surface of conduit 40. As such, conduit40 with heated surfaces serves as an active radiator. The arrows fromconduit 40 to reactor module 50 representing radiant heat transfer, andthe arrows from insulating member 60 to reactor module 50 representingradiant heat reflected back to reactor module 50. Reactor modules 50surround heated conduit 40 for surface-to-surface radiative heattransfer. The hot gases, upon exiting conduit 40, turn and pass overreactor modules 50, first transversely and then in parallel to provideconvective heat transfer as indicated by the arrow exiting passage 46and curved arrows along the length of the reactor module 50. In someembodiments, the convective heat transfer indicated by the arrow exitingpassage 46 and curved arrows along the length of reactor module 50occurs all around the circumference of reactor module 50.

The high radiation from conduit 40 surface can effectively heat thelower portion of reforming modules 50 where the surface temperature canbe lower. The radiation can also smooth out temperature gradients onreactor modules 50 over a substantial portion of their length. Thetemperature of the hot gases exiting conduit 40 can be generally lowerthan the one without radiation occurring on the conduit wall. Thecombination of surface-to-surface radiation and convective heat transfercan maintain peak temperature of the module walls at a lower temperatureand at the same heat transfer duty, a key consideration in achievinglonger reformer lifetimes.

FIG. 3 depicts an embodiment of the present disclosure where first end90 of shell 10 includes a plurality of openings 70, wherein each opening70 can be configured to receive reactor module 50. In some embodiments,reactor module 50 can be individually inserted to extend into cavity 20of the shell 10.

FIG. 4 depicts a cross-sectional view of the embodiment shown in FIG. 2.As shown, a surface of insulating member 60 can be designed to provide aradiant reflective surface geometry. For example, a surface facing aportion of reactor module 50 disposed within cavity 20 can be shaped toconform to the shape of said portion of reactor module 50 and sized toprovide space 25 between said portion of reactor module 50 and saidsurface of insulating member 60. High temperature heat media can flowthrough the space 25 in an optimal velocity considering convective heattransfer rates, flow uniformity, pressure drop, mechanical tolerance,assembly requirements and cost. In some embodiments, the geometry of theat least one insulating member provides that the radiant beams from thesurface of the radiant element arriving at the surface of the reactormodule are intercepted and deflected back by the surface of theinsulation member to the reactor modules. In other embodiments, the atleast one insulating member comprises arc shapes the number of which canmatch the number of the reactor modules. In other embodiments, thelength of the at least one insulation member can be about the same orsubstantially the same as the length of the cylindrical shell forradiant reflection and metal shell protection.

FIG. 5 depicts another embodiment of the present disclosure wherein theportion of reactor module 150 that remains outside of cavity 120 can beindividually and removably attached to top portion 190 of shell 100. Forexample, portion 152 can be attached to top portion 190 by such means asclamps, bolts, or other mechanisms known in the art. In someembodiments, portion 152 can be removably attached to top portion 190without welding and can have the advantage of quick removal and/orreplacement of reactor module 50 as a method of servicing the steamreformer. In other embodiments, portion 152 can be removably attached tobottom portion 180 (not depicted).

In some embodiments, portion 154 of reactor module 150 disposed withincavity 120 freely hangs within the interior space without attachment tothe inner surface of the shell near bottom portion 180 of the shell 100.In one embodiment, portion 154 can be attached to the inner surface ofthe shell near bottom portion 180 of the shell 100, for example, withpigtail pipes (not depicted), which are flexible gas conduits betweentwo connection points allowing for differential thermal expansion and/ordisplacement, or means otherwise known in the art. In other embodiments,portion 154 of reactor module 150 disposed within cavity 120 freelyhangs within the interior space without attachment to the inner surfaceof the shell near bottom portion 180 of the shell 100. In oneembodiment, portion 154 is free from such connections within the cavityas, for example, pigtail pipes.

In some embodiments, bottom portion 180 can comprise opening 185 whereinconduit 140 can be attached at second end 144 of conduit 140. In someembodiments, a reactant entry port and a product exit port of thereactor module are both connected to the top portion of the reactormodule or the bottom of the reactor module. In other embodiments, areactant entry port and a product exit port are on different portions ofthe reactor module.

In another embodiment, cooling coil 160 can cool the exhaust streamexiting from the reformer. In some embodiments, the cooling coil can beseparated from the burner/reformer assembly.

FIG. 6 depicts another embodiment of a reforming module 50 of thepresent disclosure. In this embodiment, reactor module 50 can be avessel with an exterior surface designed to accept thermal input fromthe exterior region (e.g. radiation from the surface of conduit member40 and insulation members 60 and 65, and convection from hot gases fromconduit member 40 (not pictured)). The thermal input can pass into theat least one reforming catalyst, driving the endothermic reformingreaction. Reactor module 50 can be a vessel, tube, pipe, duct or otherstructure as discussed above.

Reactor module 50 can be installed or replaced from outside of thereformer. Each reactor module 50 can be installed either from top orfrom the bottom of the reformer. The module outside shape can be round,square, triangle or any other shapes. Reactor module 50 can beconstructed of such materials as any inorganic materials such as glass,ceramic, stainless steels, exotic alloys, metal alloy as describedabove, etc. depending on operating pressure and temperature.

In this embodiment, reactor module 50 can comprise a cavity and containsa multiplicity of flows spaces nested together and configured in such away to induce multiple countercurrent flows. In some embodiments, thenested flow spaces comprise a tube assembly disposed at least partiallywithin the cavity of reformer 50. Specifically, reactor module 50includes a first fluid conduit that, in this embodiment, is shell 200that includes a first end 210, a second end 220, and a passage extendinggenerally between first end 210 and second end 220. Reactor module 50also can comprise second fluid conduit 250 disposed within the passageof the first fluid conduit. Second fluid conduit 250 includes first end252, second end 254, and passage 256.

A third fluid conduit 260 can be disposed within passage 256 of secondfluid conduit 250 and includes a first end 262, a second end 264, and apassage 266. A fourth fluid conduit 270 can be disposed within passage266 of third fluid conduit 260 and includes a first end 272, a secondend 274, and a passage 276. The passage of first fluid conduit 200 alsocan comprise reforming catalyst bed 230 which can comprise at least onereforming catalyst. First end 272 of fourth fluid conduit 270 furtherincludes reactant entry port 310, and first end 210 of first fluidconduit 200 includes product exit port 320.

Second end 220 of first fluid conduit 200 and second end 274 of fourthfluid conduit 270 can be fluidly connected allowing for fluid flow of areactant stream to pass through fourth fluid conduit 270 to reformingcatalyst bed 230. In some embodiments, reactant entry port 310 andfourth fluid conduit 270 can function as a first channel configured toprovide a reactant stream to at least a portion of catalyst bed 230.

Reforming catalyst bed 230 can be fluidly connected to second fluidconduit 250 at first end 252 allowing for fluid flow of a product streamto pass from catalyst bed 230 to second fluid conduit 250. Second end264 of third fluid conduit 260 and second end 254 of second fluidconduit 250 can be fluidly connected allowing for fluid flow of aproduct stream to pass from second fluid conduit 250 to third fluidconduit 260. First end 210 of first fluid conduit 200 and first end 262of third fluid conduit 260 can be fluidly connected allowing for fluidflow of a product stream to pass from third fluid conduit 260 to firstfluid conduit 200 and out reactant exit port 320. In some embodiments,second fluid conduit 250, third fluid conduit 260, and first fluidconduit 200 can function as a second channel configured to pass areactant stream from catalyst bed 230 to reactant exit port 320.

A hot product stream passing from reforming catalyst bed 230, throughsecond fluid conduit 250, and third fluid conduit 260 can pre-heat areactant stream passing through fourth fluid conduit 270 counter-currentto the product stream flow, by heat transfer between the product streamand the reactant stream. The hot product stream passing from reformingcatalyst bed 230 can also heat all or some of reforming catalyst bed 230through the significant amount of wall surface of the second fluidconduit 250 contiguous with reforming catalyst bed 230.

The reactor module embodiment depicted in FIG. 6, which compriseconcentric, internal, countercurrent flow passages partitioned by secondfluid conduit 250, third fluid conduit 260, and fourth fluid conduit270, can provide relatively low temperatures at both ends of shell 200.Such a temperature profile can ease the welding requirements, and allowuse of lower cost materials versus costly exotic alloys under certainoperating pressure ranges. Thus, reactor module 50 can be constructed ofcommon stainless steel pipes and caps and fabricated by welding andother methods known in the art. Second fluid conduit 250, third fluidconduit 260, and fourth fluid conduit 270 can be constructed of commonstainless steel pipes or tubes such as SS316, and fabricated by weldingor other methods known in the art. These materials and methods ofmanufacturing can be utilized because of low pressure differentialsacross the walls of the above three conduits.

Additionally, the relative cold reactant stream can be fed throughfourth fluid conduit 270 without reducing the temperature of reformingcatalyst bed 230. This enables high efficiency internal heat recoveryfrom a hot product stream to a cold reactant stream. Further, theinternal heat transfer can alleviate the need for an external heatexchanger to cool a hot product stream and preheat a cold reactantstream thereby simplifying a steam reformer such as, for example, asteam reformer of the present disclosure.

FIG. 7 depicts another embodiment of a steam reformer of the presentdisclosure. In this embodiment, the shell may further comprise at leastone deflector 300 disposed about the first end of conduit 40. Deflector300 may also be interposed between radiant conduit 40 and reactionmodule 50.

Without wishing to be bound by any particular theory, the temperaturedifference between a hot spot on the front wall of reaction module 50facing the hot gases exiting conduit 40 and the back side of thereaction module 50 can reach over 100° C. This temperature differencecan cause the reaction module to deform in the radial direction and makecontact (with some force) with insulating member 60. This deformationcan change the flow behavior near the bottom of reaction module 50(narrower gap between insulating member 60 and reaction module 50), butalso can damage insulating member 60 when temperature differenceincreases. In this embodiment, deflector 300 can block hot combustiongas 310 exiting conduit 40 from impinging onto reaction module 50 byreflecting hot gasses 320 and send more hot gas flow to the back ofreaction module 50 along path 330, which may result in a lower frontwall temperature of reaction module 50 and enhanced convective heattransfer on the back side of reaction module 50.

The deflectors 300 may have any suitable size, shape and/orcross-sectional area to, for example, block hot combustion gas exitingconduit 40 from impinging onto reaction module 50, and/or send more hotgas flow to the back of reaction module 50, and/or reduce thetemperature difference about reaction module 50 so any radialdeformation may be decreased.

FIG. 8 depicts yet another embodiment of a steam reformer of the presentdisclosure. In this embodiment, insulating member 60 may furthercomprise at least one reflector 400 disposed about the first end ofconduit 40. Reflector 400 may also be interposed between insulatingmember 60 and reaction module 50 and may be located at any positionabout insulating member 60.

Without wishing to be bound by any particular theory, reflector 400 mayreflect radiation energy to the back of reactor module 50 relative toconduit 40 resulting in a lower temperature difference between the frontand back of reactor module 50 relative to conduit 40. This may alsoreduce any radial deformation at the bottom of reactor module 50.

The reflector 400 may have any suitable size, shape and/orcross-sectional area to, for example, reflect radiation energy to theback of reactor module 50 relative to conduit 40 so that any radialdeformation may be decreased.

In some embodiments, reflector 400 and deflector 300 may eachindependently comprise at least one high conductivity, high emissivitymaterial each independently selected from a metal, a porcelain, a metalalloy, a glass, a ceramic, a silicon carbide, and combinations thereofas discussed above regarding conduit 40. In one embodiment, reflector400 comprises a silicon carbide.

In some embodiments, deflector 300 and reflector 400 may eachindependently comprise a high temperature alloy, and can be constructedby cutting, welding, casting, or any other method known in the art.Non-limiting examples of metal include tungsten, nickel, chromium, iron,aluminum, stainless steel, and mixtures or combinations thereof asdiscussed above regarding reactor module 50. Non-limiting examples ofmetal alloys include alloys comprising at least one of nickel, iron,cobalt, chromium, molybdenum, tungsten, silicon, manganese, aluminum,carbon, and mixtures or combinations thereof as discussed aboveregarding reactor module 50.

Other embodiments of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the concepts disclosed herein. It is intended that the specificationand examples be considered as exemplary only, with a true scope andspirit of the present disclosure being indicated by the followingclaims.

What is claimed is:
 1. A steam reformer for the production of a hydrogenreformate, comprising: a cylindrical shell defining a cavity having abottom portion comprising an opening; a heat source configured to heat afluid supplied to the cavity; a silicon carbide hollow conduitcomprising openings at both ends, a first end of the conduit is disposedwithin the cavity and opens into the cavity and a second end of theconduit is attached to the bottom portion of the shell and opens to theshell exterior, wherein the heat source is in fluid communication withthe second end, and the silicon carbide hollow conduit guides the heatedfluid from the heat source to the cavity; a plurality of cylindricalreactor modules as least partially disposed within the cavity arepositioned around the silicon carbide conduit to receive heat suppliedby the heated fluid and radiant heat supplied by the silicon carbideconduit, wherein each reactor modules includes a reforming catalyst bed;and at least one insulating member disposed about the cavity surroundingthe plurality of reactor modules, wherein a surface of the at least oneinsulating member facing at least one reactor module is shaped toreflect radiant heat from the silicon carbide conduit and the at leastone reactor module, and heated fluid back to the at least one reactormodule.
 2. The steam reformer of claim 1, wherein the insulating memberdefines semicircular shaped spaces conforming to the shape of thereactor modules and wherein the number of semicircular shaped spacesmatches the number of the reactor modules.
 3. The steam reformer ofclaim 1, wherein the reforming catalyst bed comprises at least one of astream reforming catalyst, a pre-stream reforming catalyst, an oxidationcatalyst, a partial oxidation catalyst, and a water-gas-shift catalyst.4. The steam reformer of claim 1, wherein the plurality of reactormodules each include at least one thermally emissive and radiantabsorptive material selected from the group consisting of a metal, ametal alloy, a glass, a ceramic, a silicon carbide, and combinationsthereof.
 5. The steam reformer of claim 1, wherein a top portion of theshell includes a plurality of openings configured to receive theplurality of reactor modules into the cavity.
 6. The steam reformer ofclaim 5, wherein each of the plurality of reactor modules is removablyattached to the top portion of the shell.
 7. The steam reformer of claim1, wherein a length of the silicon carbide hollow conduit is equal to orgreater than the length of the reforming catalyst beds of the pluralityof reactor modules.
 8. The steam reformer of claim 1, wherein a lengthof the silicon carbide hollow conduit is equal to or less than thelength of the reforming catalyst beds of the plurality of reactormodules.
 9. The steam reformer of claim 1, wherein the heated fluid forthe silicon carbide hollow conduit and the plurality of reactor modulescomprises a hot gas produced by at least one method selected from thegroup consisting of burning a fuel with air, converting electricity,focusing solar beams, and combinations thereof.
 10. The steam reformerof claim 1, wherein a portion of each reactor module disposed within thecavity freely hangs therein.
 11. The steam reformer of claim 1, furthercomprising a plurality of deflectors disposed about the first end of theconduit configured to direct the heat fluid around the reactor modules,thereby reducing a temperature difference about each reactor module. 12.The steam reformer of claim 1, wherein the plurality of deflectors areformed of at least one of a metal, a porcelain, a metal alloy, a glass,a ceramic, a silicon carbide, or combination thereof.
 13. The steamreformer of claim 1, further comprising a plurality of reflectorsdisposed between the insulating member and each of the plurality ofreactor modules.
 14. The steam reformer of claim 1, wherein theplurality of reflectors are configured to reflection radiation energyaround the reactor modules to reduce temperature difference around thereactor modules and thereby reducing radial deformation of the reactormodules.